France (76 years) was third, Singapore fourth (76 years) and Kuwait fifth (75.3 years) in the age-related disease burden rankings. At 68.5 years, the United States ranked 54th, between Iran (69 years) and Antigua and Barbuda (68.4 years).

"The findings show increased life expectancy at older ages can either be an opportunity or a threat to the overall welfare of population, depending on the ageing-related health problems the population experiences regardless of chronological age." said Angela Y Chang, lead author from the University of Washington.

Age-related health problems can lead to early retirement, a smaller work force, and higher health spending.

"Government leaders and other stakeholders influencing health systems need to consider when people begin suffering the negative effects of ageing," Chang said.

The negative effects, include impaired functions and loss of physical, mental, and cognitive abilities resulting from the 92 medical conditions analysed -- five of which are communicable and 81 non-communicable, along with six injuries.

To reach the conclusion, the researchers measured "age-related disease burden" by aggregating all disability-adjusted life years -- a measurement of loss of healthy life, related to the 92 diseases.

Using global average 65-year-olds as a reference group, Chang and the team also estimated the ages at which the population in each country experienced the same related burden rate.

The study covered the period of 1990 to 2017 in 195 countries and territories.